1. Field of the Invention
The present invention relates to an electrical connector terminal for a flexible printed circuit board and more particularly to a terminal which provides more reliable mechanical and electrical connection to the circuit board.
2. Description of the Prior Art
Several types of electrical connector terminals have been used for flexible printed circuit boards. FIGS. 4a and 4c illustrate one type wherein the terminal has an elongated plate-like strip 41 with integrally formed projections 42 extending upward at the sides. The strip portion of the terminal is located under a conductor 5a of a flexible printed circuit board 5 so that the projections 42 penetrate the circuit board at both sides of the conductor 5a. The ends of projections 42, which are sticking out of the top surface of the board, are then bent onto the conductor 5a of the flexible circuit board and fixed directly to the conductor by crimping for electrical connection, as shown in FIG. 4c. Another variation of this type of terminal for a flexible circuit board is shown in FIGS. 4b and 4d. In this variation, the terminal has a group of projections 42 extending from the flat upper surface of its plate-like strip 41. Thus, when located beneath a conductor 5a of the flexible circuit board, the projections 42 will penetrate the board and conductor 5a directly from below. The projections 42 are then bent and crimped directly to the conductor 5a by crimping as shown in FIG. 4d. In both the foregoing examples, the clamping force exerted by the ends of the projections 41 is small since the circuit board onto which the ends are directly fixed by crimping is flexible. The junction between the flexible circuit board and the projections are therefor more likely to be loosened by external factors such as heat, vibration, the bending of the circuit board and the like, thereby making the electrical connection unstable.
FIG. 5 shows another prior art terminal which is somewhat similar to the terminal disclosed in U.S. Pat. No. 3,997,233 issued Dec. 14, 1976 to Robert F. Evans and assiqned to same assignee as present application. The terminal in FIG. 5 comprises two contact pieces 51 and 52 which are adapted to hold a flexible printed circuit board between them. Piece 51 has opening 53, while piece 51 is formed with projection 54 which can be fitted into opening 53. The flexible printed circuit board is clamped between contact pieces 51 and 52 of the terminal so that projection 54 of piece 52 penetrates the conductor portion of the flexible circuit board and sticks out behind piece 51 through opening 53. The projecting end of projection 54 is bent and fastened to the reverse side of contact piece 51 by crimping. In this arrangement, contact piece 51, on which projection 54 is directly fitted by crimping, is a strong metal piece, so that the terminal can clamp the flexible printed circuit board firmly. However, since the flexible circuit board is formed with a cut across its conductor which is adapted to be penetrated by projection 54, the conductor is fragile and may possibly be broken, depending on its pitch of arrangement.